Wireless communication environments of recent years are facing the problem of depletion of frequency resources, which has been caused by soaring amounts of data traffic. Thus, active discussions have been exchanged with regard to a framework for opening frequency bands that were authorized for use by specific business operators but are not being used for secondary communication. The framework for secondary communication is referred to as Licensed Shared Access (LSA). For example, the European Conference of Postal and Telecommunications Administrations (CEPT) suggests technical requirements for devices that secondarily use so-called “TV white spaces” (White Space Devices, or WSDs) that are not being used for television broadcasting in Non-Patent Literature 1 below.
Generally, transmission power of a transmitter that uses a frequency band secondarily is restricted from causing unfavorable interference with a receiver of a primary system. For example, Non-Patent Literature 1 below proposes deployment of a geo-location database (GLDB) which provides information on the coverage of digital terrestrial television (DTT) systems that are primary systems, positions of DTT receivers, tolerable interference levels, and the like in order to appropriately control transmission power of a WSD. Since use of frequency bands is normally authorized by country (or region), a different GLDB may be deployed for each country (or region).
Non-Patent Literature 3 below proposes, for example, a country or a third party installing an advanced geo-location engine (AGLE) which uses information provided from a GLDB for maximizing a system capacity of a secondary system through more advanced calculation. The frequency managing agent of the UK, the Office of Communications (OfCom), and a third party database provider have decided to employ the approach of installing an AGLE.
In addition, in Non-Patent Literature 4 below, a technology of coexistence of devices which use a frequency band secondarily is discussed.